The applicant of the subject application has disclosed, in Patent Publication 1, a packaging bag with a fastener, in which a spout unit for pouring out a content is provided as a member independent of a bag body, and the spout unit is connected to an attachment opening formed to the bag body. The packaging bag with a fastener disclosed in this Patent Publication 1 is provided with a fastener to the inner surface of a wall portion forming the spout portion.
According to the development of such fastener packaging bag as disclosed in the Patent Publication 1, it becomes easy to maintain the packaging bag with the pouring opening being opened, which was difficult in a conventional packaging bag. This was a significant matter.
Further, there have hitherto provided many inventions disclosing a structure in which a fastener is applied to a packaging bag, and an once-opened packaging bag is re-sealed, and in such structure, the fastener are easily engaged or disengaged, and a male fastener element and a female fastener element are surely engaged together.
For example, in an invention disclosed in Patent Publication 2, a groove is formed to the front end of a male fastener element. According to this invention, even if a content accommodated in a packaging bag adheres to the inside of the groove of a female fastener element, the adhering content is accommodated inside the groove. Accordingly, the fastener elements are surely engaged, and engagement or disengagement of the fastener elements is smoothly performed.    Patent Publication 1: Japanese Patent Application Laid-open Publication No. 2005-350104    Patent Publication 2: Japanese Patent Application Laid-open Publication No. 2005-144077